China’s tax bonus is a BONUS. Find another way to change how it works other than making an already weak unit worse. Palace Guards are great in being utilized differently, but are straight up costlier and weaker versions of their original self. This becomes doubly troublesome for a civilization like Zhu Xi who does not have access to the Palace Guard health buff, making them literally trash.
In a 1 vs 1 battle, the Zhun Xi civilization has the advantage when it comes to building structures, reducing the percentage of resources needed at the start of the game. The palace guard unit is meant to defend, but it is clear that it was not created for this defensive function.